The purpose of this study was to obtain data on the secretion rates of cdb-1781 followed by intravenous (IV) and intramuscular (IM) administration. In phase I, three intact and one castrate, four intact and three intact male monkeys were assigned to dose groups I through III respectively with each group receiving two IM injections at ninety day intervals of CDB-1781 (long acting ester of testosterone) at a low, mid and high dose for groups I through III respectively. Two pre treatment blood collections were obtained, daily for one week following injection, then once per week thereafter. Circulating levels of the compound were analyzed by total androgen RIA. In phase II, two castrate monkeys were given 1 mg/ml of CDB-1781t (long-acting ester of testosterone) and 0.634 Mg/ml of CDB-111b (testosterone) in separate IV injections followed by a series of rapid timepoint blood collections. In phase I, androgen ranged from 30.0 Ng/ml (sem 5.7) To 186.6 Ng/ml (sem 31.7) Following the first injection and 33.5 Ng/ml (sem 6.1) To 182.7 Ng/ml (sem 15.4) Following the second injection for the intact monkeys in groups I through III respectively. The castrate monkey in group I had peak levels of 38.8 And 45.7 Ng/ml for injections 1 and 2 respectively. In phase II, androgen peaked at 58.5 Ng/ml (sem 17.9) And 290.2 Ng/ml (sem 92.7) Following cdb-1781t and CDB-111b respectively. A separate I.M. Injection of CDB-1781 at 1 mg/ml showed circulating levels of androgen ranging from 2.0 Ng/ml (sem 0.1) At 4 hr post injection to 0.6 Ng/ml (sem 0.1) At d-98.